@moia-oss/eslint-prettier-typescript-config
v3.0.9
Published
Shared MOIA TypeScript, eslint and prettier configuration
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eslint-prettier-typescript-config
Shared MOIA TypeScript, eslint and prettier configuration
Usage
Install
npm install -D typescript eslint prettier npm install -D @moia-oss/eslint-prettier-typescript-config # in some cases, you may need to install these packages directly: npm install -D @typescript-eslint/parser @typescript-eslint/eslint-plugin
Link configurations
(customise paths as needed)
tsconfig.json
{ "extends": "@moia-oss/eslint-prettier-typescript-config", "compilerOptions": { "outDir": "./build", "rootDir": "./src", }, "include": ["./src"], }
.eslintrc
(removereact
andstrict
if not required. more info further down in this README).{ "extends": [ "./node_modules/@moia-oss/eslint-prettier-typescript-config/config/eslint", "./node_modules/@moia-oss/eslint-prettier-typescript-config/config/eslint-react", "./node_modules/@moia-oss/eslint-prettier-typescript-config/config/eslint-strict", ], // Only add if you have a CDK directory, customise path as needed "overrides": [ { "files": ["cdk/**/*"], "extends": [ "./node_modules/@moia-oss/eslint-prettier-typescript-config/config/eslint-cdk", ], }, ], }
.prettierrc
"@moia-oss/eslint-prettier-typescript-config/config/prettier"
Add scripts to
package.json
(customise paths as needed)
{ "scripts": { "build": "tsc", "lint": "eslint ./src/", "format": "prettier . --write", "format:check": "prettier . --check", }, }
Done! Don't forget to run
build
,lint
andformat:check
in your CI workflow.
Strict eslint mode
The strict config enables a few more things that not every team may want:
Arrow (expression) function style preferred:
// Not allowed function foo() { return 1; } // Allowed const foo = () => { return 1; };
Type assertions not allowed:
Due to the design goal of type erasure (no runtime overhead), type assertions are not ever checked.
When you assert a type, it may look suspiciously like type casting in a language such as Kotlin, but it isn't the same thing. TypeScript just "trusts" you and doesn't check the type.
At runtime, you wouldn't get a cast error if the type is not the same, but only see a problem if you try to access or use a value that doesn't match the expected type.
Use parsing libraries such as zod.
// Error: type Foo = { x: 1; }; // no error thrown, silently continues const foo = JSON.parse('{"y":1}') as Foo; // evauluates silently to NaN: foo.x + 1; // this also silently continues: const bar = JSON.parse('{"xyz":1}') as { x: { y: number } }; // you won't see a problem in runtime until somewhere // else in the code, making it hard to trace: // throws `Uncaught TypeError: Cannot read property 'y' of undefined` console.log(bar.x.y);
// OK: import * as z from 'zod'; const FooSchema = z.object({ x: z.number(), }); type Foo = z.infer<typeof FooSchema>; // parses successfully const foo = FooSchema.parse(JSON.parse('{"x":1}')); // throws an error detailing why the JSON doesn't match const bar = FooSchema.parse(JSON.parse('{"y":1}'));
Optional Additions
VSCode lint/format settings in
.vscode/settings.json
{ "editor.formatOnSave": true, "editor.defaultFormatter": "esbenp.prettier-vscode", "editor.codeActionsOnSave": { "source.fixAll.eslint": true, }, }
VSCode extension recommendations in
.vscode/extensions.json
{ "recommendations": ["esbenp.prettier-vscode", "dbaeumer.vscode-eslint"] }
.editorconfig
[*] end_of_line = lf insert_final_newline = true charset = utf-8 indent_style = space indent_size = 2
Config Development
This relates to the development of this package. Ignore this section as a consumer.
This package uses its own exported config to build, lint and format itself. This also makes sure that the configs are valid, as the steps are run during the GitHub Actions build step.
Because of this, you must run npm run build
before linting or formatting during development
Husky hooks
Husky is used to introduce git hooks.
Link to the package https://typicode.github.io/husky/
To install them, execute npm run husky:prepare
Release
We will automatically release on push to main. Make sure to update the package version according to your change following semantic versioning